Applying mental model methods to characterize understanding of gene-environment influences: the case of podoconiosis in Ethiopia

The rapid pace of genomic discovery has raised public expectation and concerns about the utility of new discoveries and their potential to exacerbate health disparities. Improving literacy concerning gene and environmental (GxE) contributors to disease is needed to avoid commonly observed deterministic misconceptions about genomics. Mental models approaches that incorporate community engagement processes could be used to inform GxE literacy-building interventions. We used a mental models approach to describe and systematically compare expert and lay understanding of GxE interactions, using the example of podoconiosis, a non-infectious lymphedema endemic in highland Ethiopia. Methods included: (1) specifying elicitation questions for a literature review, (2) eliciting an expert model, (3) eliciting a lay model, and (4) comparing the two models. We used a coding scheme to identify lay participants’ knowledge gaps, misunderstandings, and extra knowledge relative to the expert standard. Results indicated that lay participants’ viewed poverty as an important susceptibility factor and considered heredity and contagion to have a joint causal influence. Experts did not endorse either of these viewpoints. Conventional expert-based interventions aimed to correct misconceptions about behaviors important for prevention may be stymied by lay views that social environmental factors have more important influences on health outcomes. GxE literacy interventions that consider multiple levels of influence including social determinants of health and personal resilience to augment health education strategies are needed in diverse settings. Novel communication approaches will be needed to help target audiences disentangle long-held conceptions of heredity and contagion.     

Attack rates of human papillomavirus type 16 and cervical neoplasia in primiparous women and field trial designs for HPV16 vaccination

BACKGROUND: Identification of human papillomavirus type 16 (HPV16) as the major risk factor for cervical neoplasia, and mass production of DNA free HPV capsids have paved the way to preventive vaccination trials. Design of such trials requires reliable attack rate data. OBJECTIVE: Determination of (1) HPV16 and (2) cervical neoplasia attack rates in primiparous women. Estimation of actuarial sample sizes for HPV16 vaccination phase IV trials. DESIGN: A longitudinal cohort study. METHODS: Population based Finnish Maternity Cohort (FMC) and Finnish Cancer Registry (FCR) were linked for the identification of two cohorts of primiparous women: (1) a random subsample of the FMC: 1656 women with two pregnancies between 1983-9 or 1990-6 and living in the Helsinki metropolitan area, and (2) all 72,791 primiparous women living in the same area during 1983-94. Attack rate for persistent HPV16 infection (1) was estimated in 1279 seronegative women by proportion of seroconversions between the first and the second pregnancy. Comparable 10 year cumulative incidence rate (CR) of cervical intraepithelial neoplasia grade III and cervical cancer (CIN III+) (2) was estimated based on cases registered at the FCR during 1991-4. RESULTS: The HPV16 attack rates were 13.8% (< 18 years), 7.0% (18-19 years), 2.3% (21 years), 2.4% (23 years), and 4.5% (< 25 years). Number of vaccinees required for a 5 year efficacy trial with persistent HPV16 infection as the end point ranged between 1000 and 3900, assuming 80% power, 90%-70% vaccine efficacy (VE), and misclassification. The CRs of CIN III+ were 0.33% (< 18 years), 0.44% (18-19 years), 0.21% (20-24 years), and 0.28% (< 25 years). Number of vaccinees required for a 10 year efficacy trial with HPV16 positive CIN III+ as the end point was 15,000 assuming 80% power, 90% VE, and 75% aetiological fraction of CIN III+ for HPV16. CONCLUSIONS: The attack rates of HPV16 and CIN III+ identify primiparous women under 25 years of age among target populations for postnatal HPV vaccination at phase II/III trials.     

Seropositivity to multiple sexually transmitted infections is not common

BACKGROUND: Seropositivity for several sexually transmitted infections (STIs) is often used as a surrogate measure of sexual behavior. The authors assessed the concomitant seropositivity for STIs in women. GOAL: To estimate the excess of concomitant seropositivity for four STIs among fertile-aged women assuming no coinfections above what would be expected at random. STUDY DESIGN: Antibodies to herpes simplex virus type 2, human papillomavirus type 16, HIV, Chlamydia trachomatis, and Treponema pallidum were determined from a random sample of 1110 pregnant women in Tallinn, Estonia. RESULTS: A total of 310 combinations of the concomitant seropositivity were observed, whereas only 193 were expected by chance. Among persons seropositive for two STIs, 78 extra combinations were observed, whereas for three STIs, 35 extra combinations were observed. For four STIs, 3.8 extra combinations were found. CONCLUSIONS: Seropositivity to multiple STIs is not common. This fits the concept of different transmission probabilities and the spread of the STIs, and suggests that seropositivity alone should be used with caution as a surrogate to sexual behavior in women.     

Prospects for phase III-IV HPV vaccination trials in the Nordic countries and in Estonia.

BACKGROUND: oncogenic, i.e. high risk human papillomavirus (hrHPV) types are the major cause of invasive cervical cancer (ICC). Putatively licensable vaccines against the hrHPVs have been developed and are approaching clinical phase III trials that use persistent HPV infection as end point. Direct extension of the phase III trials towards long-term end points (ICC and its immediate precursors: carcinoma in situ and severe dysplasia, i.e. cervical intraepithelial neoplasia grade III, CINIII) is important, to avoid early contamination of the target population by opportunistic use of licensed HPV vaccines. Country-wide registration on population and health events in a stable population of 25 million make Estonia and the Nordic countries a unique venue for long-term evaluation of cervical cancer control measures. Mass-screening programmes exist in all Nordic countries, but not in Estonia. AIM: design of phase III-IV trials for evaluation of protection against ICC and CINIII by preventive HPV vaccines based on cancer registry follow-up. RESULTS: in the Nordic countries, population based randomisation of all 15-year-old women to the vaccination (vaccine and placebo) and reference cohorts entering conventional Pap-smear screening after a clinical phase III trial would assure comparability of the cohorts. Enrollment of 10094 vaccinees +10094 placebo vaccinees +30282 other hrHPV negative women without vaccination at the age of 16 would give 80% power for the demonstration of 70% vaccine efficacy (VE) against ICC in 20 years by cancer registry follow-up. On the other hand, vaccination of 8303 Estonian hrHPV negative women among the entire 15-year-old female birth cohort (about 10000 women) with an already licensed HPV vaccine would enable demonstration of 70% VE against ICC by 20 years of registry follow-up of these and comparable 16606 women identified among the 16-19-year-old birth cohorts. CONCLUSIONS: evaluation of the protective effect of an HPV vaccine against ICC is possible both in countries with or without mass-screening. The effects of vaccination on spread of different HPVs in the population would need to be monitored, especially in Estonia. Ethical aspects, cost-benefit evaluation and comparisons with other new means of cervical cancer control warrant further investigation.